Electromagnetic telephone.



No. 655,||3. Patented July 3l, |900.

A. PLECHER. ELECTRUMAGNETIC TELEPHONE.

lApplication led Feb. 16, 1900.)

(No Model.)

w/TNESSES .I

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ANDRE W ILEOIIER, OF

ATENT Frisia,

SAVANNAH, GEORGIA.

SPECIFICATION forming part of Letters tPatent No.-655,113, dated July 3l, 1900. Application nea rtuafyi, 1900. strain). 5,443. (Numan.)

T0 @ZZ whom, it may concern:

Be it known that I, ANDREW PLECHER, of Savannah,in the county of Chatham and State of Georgia, have invented a new and useful Improvement in Electromagnetic Telephones, of which the following is a specification.

My invention is in the nature of an electromagnetic telephone transmitter and receiver which may also be used as a repeater; and it consists in the peculiar construction and arrangement of parts acting upon new principles, as will be hereinafter fully described with reference to the drawings, in which- Figure l represents a sectional view of two combined transmitters and receivers connected at the opposite ends of a line and marked Nos. 1 and 2, and Fig. 2 shows a further development of the same.

M is an iron magnetic box which by an iron wire I is connected to a similar iron box at the other end of the line.

D and D' are two thin iron diaphragms, which are insulated from each other by a nonconducting marginal ring N, Whose joint with the diaphragms is perfectly air-tight.

Pis a handpu mp constructed conveniently as a rubber bulb and which by compression is enabled to place the air in the hermeticallysealed chamber between diaphragms D D und der a regulable tension for the purpose hereinafter described. Behind the diaphragms in the box M there is a chamber having an external opening O, preferably at the bottom, and provided with a lip or ear E, extending down below it for the admission and egress of air and sound-waves.

K is an insulated copper wire connected at one end to one pole of the battery B and after being wound around the central stem of the iron box is connected by a binding-post to the front diaphragm D. This winding makes a magnetof the box M and iron wire I. This wire K has atK' a counterpart which con-V nects with the other pole of the battery and is wound continuously around the larger iro'n wire I all the way to the next station, No. 2, and there connects with the box M and diaphragm D in the same way as at No. 1. The wire I is a large iron wire, and K' is a small silk-covered wire whose cross section and winding are such as to give it the same resist-A ance as the larger iron wire I.

Between the two diaphragms D and D' there is suspended by silk threads f a coil X of fine wire, preferably iron, whose surfaces are bare and wound so that the individual turns nearly touch each other.- One end of this coil is elec trically connected to one diaphragm D and the other end to the other diaphragm D', the connection being made by adjusting screws s s' to regulate the tension of the coil. When anoelectric current passes through this coil, the individual turns will touch, since the coil becomes magnetic. The vibrations of the diaphragms will separate or bring into contact the individual turns of the coil, whereby resistance is thrown in or eliminated from the circuit, and this causes a corresponding iiucrent passing through the coil X, its magnetic action causes the turns or convolutions to be attracted to a partial lateral contact. Then when the vibrating diaphragms move outwardly this lateral contact between the convolutions is broken and the resistance of the whole coil will be thrown in by compelling the current to traverse the coil lengthwise instead of jumping across from convolution to convolution by a shortcircuiting contact. When the voice produces air vibrations, these act through the mouthpiece W on the front face of the diaphragm D and also entering opening O act on the back face of the diaphragm D', causing the two diaphragms to vibrate in opposite directions and augmenting the effect on the resistancewarying coil X one hundred per cent. The fluctuations are transmitted over the double line both by electrical current and by magnetism on account of the arrangement of the wires K' and I.

In the action of the telephone the circuit is made as follows: from battery B to wirenI, diaphragm D, resistance-coil X,`diaphragm D', iron box M, iron wire I to the iron box of the other station, No. 2, thence to''the diaphragm D' of that station, through the resistance-coil X of that station, to diaphragm D, and thence by wire K K' back over the line to the other side of battery B.

ICO

The object of the air-bulb P is to cause l the hermetically-sealed chamber between phone.

the diaphragmstobe expanded orcollapsed tolegulateV Vatfwillthe'famplitude `of move ment ofthe turns ofdthefcoil AX. v l Ifwdo not claim, broadly, lan air-bulbiorl exhausting the ain-.behind a telephone-diaphragm, as Iham aware that this is-old-f I7 am also aware that double diaphragms with` resistance-varying media between them are` old and I makeuno broad claimtothe' same.;

In usingthis telephone for arepeate'r it is only necessary to connect the two diaphragms D andD." with two circuit-'wiresAand A,1re spectively, and to carry these to athird te1e. I have shown a pair of wires AA at bothfthe station No. l and the station No. 2. These wires are mere duplicates of each other to connect a repeating-telephone with the inl strument at either station No. l or No, 2.y n lIn rendering my'transmittei` more sensitive I may constructit as shown in Fig. 2, in which the ends of the coil X have carbon` buttons p p', mounted on metal disks at the ends of the coiland in electric connection with theY said coil andsustained only lcyltheV threads f and yarranged to bear with an elastic y pressure against the diaphragm-plates D D. Having thus described my invention, what Iclaim as new, 4and desire to secure by Letters Patent, is-L l 1. A 'resistance-varying medium for a tele;

, phone consisting of a coil of Iine bare'wire of magnetic metal having separated turns or convolutions interposed in the ycircuit and y arranged as described to, collapse and reduce resistance from magnetic action substantially as set forth.

2. A'resistiance-varying medium for a tele- Vphoneconsisting of a coil of tine bare wire l of-magneticiimetalhaving-separated turns or convoltions,A combined with two diaphragms connected respectively to the opposite ends of isaidcoiland vibrating in oppositev directions as set forth.

\- 3. VVAtelephonecomprising an iron box and Vdiaphragms having between them aresist- ,ance-varying medium withina hermeticallysealed chamberand' meansfor' increasing or' decreasing'the'air-pressure within said her `meticzally-sealed chamber substantially as described.` v v Y t 5. The combination with the diaphragm,-

plates D D; of the interposed wire coil X Vhavin g carbon pieces at its ends in elastic contact with vthe'plat-es D D substantially'as described. n Y l y 6. A telephone comprising an iron boX M having an iron wireI connecting it to asimilar iron boX, a battery-circuit wire coiled about the same, said battery-'circuit wire being connected with .thel iron bontl through a variableresist'ance medium anda diaphragm substantially as described. Y

'Inl testimony whereof I have' signed ymy name to this specification inthe presence of two subscribing witnesses.

` ANDREW PLECHER. Witnesses: A. MCQU'ADE,

PAT-RICK SMITH. 

